Pipette



M. C. SANZ Jan. 221, 1964 PIPETTE Filed Jan. 6, 1961 INVENTOR Ham/el C5602 BY 2 x/aww.

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lgatented dan.

This invention relates to pipettes for transferring predetermined reproducible quantities of liquids.

This application is a continuation-in-part of US. Application Serial No. 652,265, now US. Patent No. 2,974,528, filed April 1l, 1957. ln that application, there are disclosed pipettes which include the container or reservoir for the liquid to be transferred in reproducible quantities. Such pipettes comprise a measuring tube with one end extending into a chamber into which the iquid from the container or reservoir may be forced; the chamber has an outlet to the atmosphere which may be closed to force liquid from the chamber into the measuring tube and thea opened to allow excess liquid to ow back into the reservoir when the outlet to the atmosphere is opened and pressure released. ln order to deliver the liquid retained in the measuring tube, the outlet of the chamber is iirst closed and then pressure is applied to the reservoir which will force the liquid out of the measuring tube.

Among the objects of the present invention is to provide a pipette similar to that disclosed in said application No. 652,265 which, however, is simpler to operate and more reliable with respect to the avoidance of air bubbles.

Another object of the present iinvention is to provide means for automatically closing the outlet of said chamber upon pressure applied to the reservoir and automaticall opening said outlet upon release of said pressure.

The objects are attained by providing that portion of the pipette measuring tube which is within the chamber with a downwardly turned end which opens downwardly towards the liquid which is forced upwardly into the chamber.

In the drawings:

FlG. 1 is a side cross sectional View of one form of the pipette of the invention.

FlG. 2 is a side cross sectional view of a modilied form of pipette.

PEG. 3 is a View of a pipette sampling bottle obtained by removing parts of the device of FIG. l0.

The pipette comprises a compressible reservoir or bottle portion 1b, a chamber forming top portion Ztl, a cap 3@ and a connecting tube 4t?. The bottle or reservoir l@ has a threaded neck 11. lt is made of flexible plastic material so that upon the application of pressure thereto, liquid is forced through tube 4i) into chamber Ztl.

The chamber 2d, as shown, is dome shaped and has a lower shoulder 2l which lits into the cap 3%, an oriice 22 in the upper portion which may be closed by a finger and an opening 23 in a side portion which is adapted to hold the plug 2d which holds the pipette measuring tube The open end of chamber Ztl also has a cylindrically extending flange 27 which interlits with an annular groove 4l of the tube portion The inner end 2S of the pipette measuring tube 25 turns downwardly as shown. In FIG. l, the liquid 12 is shown at the level it attains just as the measuring tube 25 is being filled. ln this structure there is less chance that air bubbles will be introduced along with the liquid 12 and the aspirating eiect on the tube 2S of the movement of liquid 12 back into reservoir l@ is of shorter duration.

The tube itl may be made of glass, plastic or any materim which is inert to the liquid 12. Tube 4i) has the annular shoulder 4Z adapted to be held against the neck 11 of the reservoir l@ by cap 353. The inner opening of the shoulder 42 includes the annular groove 41 into which the cylindrical ange 27 of chamber 29 lits. The diameter of the lower portion 43 of the tube may be quite small, if desired. Adjacent the funnel shaped region 44, however, an enlarged portion 45 is provided to hold a splash guard 4S or convenient size.

FG. 2 is similar to Pi. 1 except that the device of FlG. 2 contains a glass vessel dll which holds liquid 12. This device is useful where the liquid 12 attacks the material of the reservoir 1th in this case the tube dil' must also be of glass. The device of FIG. 2 operates in the same way as the device of FIG. l.

lf desired, the tube 4@ of FlG. l may be removed to produce the device shown in FIG. 3. rThe device of lllG. 3 is useful as a samp er. Thus, while the orifice 2 i held closed and the reservoir lil at least partially compressed, the nozzle 29 of measuring tube 25 may be dipped into a liquid to be sampled and the pressure on reservoir 1d released to raw the sample into tube 25. When the measuri g tube 25 is lled it is withdrawn and the contents thereof may be discharged into a suitable sample holder.

The features and principles underlying the invention described above in connection with specific exemplitications will suggest to those slrilled in the art many other modifications thereof. It is accordingly desired that the appended claims shall not be limited to any speciiic feature or details thereof.

I claim:

1. A pipette device comprising a reservoir for retaining liquid to be metered;

means forming a chamber above the reservoir;

communication means for delivering the liquid between the chamber and the reservoir in both directions;

a capillary tube of predetermined length and cross-sectional area mounted in said means for forming the chamber with a iirst end of the tube extending within the chamber and the other end extending from a side of the chamber;

the iirst end of the capillary tube extending downwardly so as to open toward said reservoir;

said means for forming the chamber including means above the level of the iirst end of said capillary tube for opening the chamber to the surrounding air.

2. A pipette device comprising a reservoir for retaining liquid to be metered;

means forming a chamber above the reservoir;

communication means for delivering the liquid between the chamber and the reservoir in both directions;

a capillary tube of predetermined length and crosssectional area mounted in said means for forming the chamber with a first end of the tube extending within the chamber and the other end extending from a side of the chamber;

said means for forming the chamber including one way valve means above the level of the lirst end of said capillary to provide communication between the inside of said chamber and the outside thereof in such a way that upon pressure applied to a fluid in the reservoir said valve is closed and immediately opened when pressure is released.

References Cited in the le of this patent UNITED eTATE-S PATENTS 

1. A PIPETTE DEVICE COMPRISING A RESERVOIR FOR RETAINING LIQUID TO BE METERED; MEANS FORMING A CHAMBER ABOVE THE RESERVOIR; COMMUNICATION MEANS FOR DELIVERING THE LIQUID BETWEEN THE CHAMBER AND THE RESERVOIR IN BOTH DIRECTIONS; A CAPILLARY TUBE OF PREDETERMINED LENGTH AND CROSS-SECTIONAL AREA MOUNTED IN SAID MEANS FOR FORMING THE CHAMBER WITH A FIRST END OF THE TUBE EXTENDING WITHIN THE CHAMBER AND THE OTHER END EXTENDING FROM A SIDE OF THE CHAMBER; THE FIRST END OF THE CAPILLARY TUBE EXTENDING DOWNWARDLY SO AS TO OPEN TOWARD SAID RESERVOIR; SAID MEANS FOR FORMING THE CHAMBER INCLUDING MEANS ABOVE THE LEVEL OF THE FIRST END OF SAID CAPILLARY TUBE FOR OPENING THE CHAMBER TO THE SURROUNDING AIR. 